Numerical analysis of re-oscillation and non-centrosymmetric convection in a porous enclosure due to opposing heat and mass fluxes on the vertical walls

Two peculiar convection patterns-re-oscillation and stable non-centrosymmetric convection-are observed when two-dimensional double-diffusive convection in a porous enclosure (aspect ratio = 1.5) is analysed numerically. The top and bottom walls of the enclosure are insulated; constant and opposing heat and mass fluxes are prescribed on the vertical walls. Re-oscillation occurs when the convection pattern changes from centrosymmetric to non-centrosymmetric. When the buoyancy ratio, which generates re-oscillation convection, is marginally lower, the convection pattern changes to stable non-centrosymmetric. These two convection patterns can be observed only for limited values of the Rayleigh number, Lewis number, and buoyancy ratio.